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Öğe Dependency of the thermal and electrical conductivity on temperatures and compositions of Zn in the Al-Zn alloys(Taylor and Francis Ltd., 2019) Erol H.; Çadirli E.; Erol E.A.; Gündüz M.The variations of thermal conductivity (K) with temperature for Al–xZn (x = 5, 10, 20, 30, 50 and 60 wt. %) alloys were measured by using a radial heat flow furnace. The variations of electrical conductivity (?) of solid phases with temperature for the studied alloys were determined from the Wiedemann-Franz and Smith-Palmer equations by using the measured values of K from the plots of K. The thermal temperature coefficient (? TTC ) and the electrical temperature coefficient (? ETC ) were obtained. Dependency of the ? TTC and ? ETC on the composition of Zn in the Al-Zn alloys was also investigated. According to the present experimental results, K of Al–Zn alloys linearly decrease with increasing temperatures up to the melting temperature for each composition and exponentially decrease with the increasing Zn content. On the other hand, the ? of Al based Al-Zn alloys exponentially decrease with increasing temperature and Zn content. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.Öğe Effects of Growth Rates and Compositions on Dendrite Arm Spacings in Directionally Solidified Al-Zn Alloys(Springer Boston, 2017) Acer E.; Çadırlı E.; Erol H.; Kaya H.; Gündüz M.Dendritic spacing can affect microsegregation profiles and also the formation of secondary phases within interdendritic regions, which influences the mechanical properties of cast structures. To understand dendritic spacings, it is important to understand the effects of growth rate and composition on primary dendrite arm spacing (?1) and secondary dendrite arm spacing (?2). In this study, aluminum alloys with concentrations of (1, 3, and 5 wt pct) Zn were directionally solidified upwards using a Bridgman-type directional solidification apparatus under a constant temperature gradient (10.3 K/mm), resulting in a wide range of growth rates (8.3–165.0 µm/s). Microstructural parameters, ?1 and ?2 were measured and expressed as functions of growth rate and composition using a linear regression analysis method. The values of ?1 and ?2 decreased with increasing growth rates. However, the values of ?1 increased with increasing concentration of Zn in the Al-Zn alloy, but the values of ?2 decreased systematically with an increased Zn concentration. In addition, a transition from a cellular to a dendritic structure was observed at a relatively low growth rate (16.5 µm/s) in this study of binary alloys. The experimental results were compared with predictive theoretical models as well as experimental works for dendritic spacing. © 2017, The Minerals, Metals & Materials Society and ASM International.Öğe Investigation of the thermo-electrical properties of A707 alloys(Elsevier B.V., 2019) Çadırlı E.; Kaya H.; Büyük U.; Şahin M.; Üstün E.; Gündüz M.In the present work, the thermal conductivity, electrical conductivity, enthalpy of fusion, specific heat capacity and thermal diffusivity of the A707 alloy (Al–4.5 Zn–1.2 Mg–0.15 Cr–0.15 Zr wt.%) have been investigated. Phase identification of the studied alloy was investigated with energy dispersive X-ray analysis and X-ray diffraction techniques. Thermal conductivity of as-cast A707 alloy was measured using Comparison Cut Bar Method in the temperature range of 300–800 K. With the increase of temperature, thermal conductivity decreased gradually in as-cast A707 alloy. The electrical conductivities of the sample were obtained with the Wiedemann–Franz equation by using the measured thermal conductivity values. Thermal conductivity coefficients for the alloy were obtained from the graphs of thermal conductivity versus temperature. The enthalpy of fusion and the specific heat capacity during the transformation were also determined. Thermal diffusivity changes were calculated as a function of temperature through the obtained thermal data. © 2019 Elsevier B.V.Öğe Solid-liquid interfacial energy of camphene(Elsevier BV, 1999) Bayender B.; Maraşli N.; Çadirli E.; Gündüz M.The Gibbs-Thomson coefficient and the solid-liquid interfacial energy for camphene have been measured to be (8.58 ± 0.96) × 10-8 K m and (4.43 ± 0.49) × 10-3 J m-2, respectively, by a direct method. The grain boundary energy of camphene has also been calculated to be (8.36 ± 0.92) × 10-3 J m-2 from the observed grain boundary groove shapes. © 1999 Elsevier Science S.A. All rights reserved.
